Is it possible to specify the percentage of query results?

Question

SQL

Hello! Please help.
There is a table with a country column. Possible values ​​are "A, B, C, D...". The sample limit is 20. Is it possible to compose a query in such a way that the result is, for example, 20% with the value A, and 80% with the value G? Or specify limits on the number of rows with value A?

Answer 1

Выбрать 20 из (Выбрать 20% для А
UNION
Выбрать 80% для Г
Сортировка (никто не знает как))